Eccentrically mounted platen structure in selective printing machines



ug- 9, 969 A. c. 'FBiAB ETAL 3,461,797

ECCENTRICALLY MOUNTED PLM'EN STRUCTURE IN SELECTIVE IRINTING MACHINES Filied Oct. 30, 1967 2 Sheets-Sheet 1 INVENTORSI Abdulrahim C. Trab Heinz Ricke Attomey Aug. 19, 1969 A. c. TRAB ET AL 3,461,797

ECCENTRICALLY MOUNTED PLATEN STRUCTURE IN SELECTIVE PRINTING mcnmss Filed Oct. 30. 1967 2 Sheet-Sheet 2 Abdulrahim C. Trab Heinz Rick: INVENTORS.

, a l I Attogncy United States Patent 12,062 Int. Cl. B41j 25/22; B41] 47/46 US. Cl. 101-96 Claims ABSTRACT OF THE DISCLOSURE A cylindrical platen, cooperating with a printing roller, is eccentrically journaled in a pair of continuously rotating end disks so as to perform a cycloidal (or, in an extreme case, rectilineal) motion parallel to itself, under the control of a planetary-gear system of the same eccentricity, whereby the platen is periodically moved toward the yieldably supported printing roller; on its swing away from the printing roller, the platen acuates a ribbon transport and a paper feed while drawing both the paper and the ribbon clear of the roller to permit resetting of its type faces.

Our present invention relates to a machine for printing or otherwise recording data registered in the form of character combinations on a presettable carrier member such as a printing roller.

High-speed printers of this description have already been proposed in which a cylindrical platen rolls on the inner surface of a cyindrical sleeve of larger diameter carrying rows of retractable type faces, the platen thus executing a cycloidal motion which brings it (or paper on its surface) into successive confrontation with the several rows of type faces during one revolution, the outer circumference of the platen and the inner circumference of the sleeve differing by a length equal to the spacing of two rows whereby the generatrices of the platen shift during successive revolutions with reference to those of the sleeve so that a given line on the platen surface 'will confront all the rows of type faces during consecutive revolutions. Reference is made in this connection to an article in the November 1960 issue of the British publication Process Control and Automation, pp. 599 and 600.

A prime object of our invention is to provide an improved system of this general type which, while utilizing the aforedescribed rolling motion, affords access to and visibility of the recorded characters during all stages of operation.

Another important object is to provide a machine of this kind which prints or othe'wise records a complete row of characters during each operating cycle, thereby reducing the total number of revolutions required for the completion of a given number of lines.

A further object of our invention is to provide means in such machine for disengaging the recording medium, e.g. a paper strip, and an associated ink ribbon (in the case of a printer) from the character carrier between operating cycles so as to enable a resetting of the characters without smudging or interference.

These objects are realized, in conformity with our present invention, by the provision of a pair of drive elements at opposite ends of the platen which are synchronously rotatable about a common axis offset from that of the platen, the ends of the platen being articulated to these drive elements at eccentric locations thereof while a co- 3,461,797 Patented Aug. 19, 1969 ice axial circular formation at each end of the platen rolls on the periphery of a respective annular track member centered on the driving axis. Advantageously, one or preferably each track member and the formation rolling thereon are toothed so as to constitute, respectively, a ring gear and a planetary gear whereby the angular position of the platen is positively determined during each revolution. The resultant transverse shifting of the platen parallel to itself brings the platen once per cycle into a position of closest approach to a juxtaposed printing roller or other carrier of characters confronting the platen whereby these confronting characters are recorded on a sheet interposed between the platen and the carrier.

According to a more particular feature of our invention, the recording medium is advanced through the gap between the platen and the character carrier in a position of substantial separation of these two members from each other, this advance being accomplished with the aid of a feed mechanism controlled by the oscillatory transverse motion of the platen itself. Thus, the platen may be journaled in its drive element through a pair of gudgeons of which at least one is engaged by a linkage designed to trip the feed mechanism during the withdrawal stroke of the platen. In a similar manner, an ink ribbon interposed between the recording medium and the printing roller may be advanced by a transport mechanism stepped in response to the transverse stroke of the platen. The recording medium and the ink ribbon may be guided and supported by elements connected with the platen so as to follow the transverse oscillations of the latter and to clear the printing roller during the resetting of its type faces. Advantageously, the printing roller is resiliently biased toward the platen so as to yield to the radial pressure from the platen in the position of closest ap proach in which printing is carried out.

The invention will be descibed in greater detail with reference to the accompanying drawing in which:

FIG. 1 is a top plan view, partly in section, of the principal elements of a data-printing machine embodying the invention; and

FIG. 2 is a cross-sectional view taken on the line IIII of FIG. 1.

The machine shown in the drawing comprises a frame 1, illustrated in part only, fixedly supporting a pair of bearing sleeves 2. The inner peripheries of these sleeves are toothed at 3 to form a pair of stationary ring gears centered on a common axis 0. Parallel to this axis 0 lies the axis P of a cylindrical platen 5, provided with a somewhat yieldable coating of hard rubber or the like, whose extremities are rigid with planetary gears 4 (only one shown) respectively in mesh with the surrounding ring gears 3. Platen 5 terminates in a pair of coaxial gudgeons 6 which eccentrically traverse a pair of driving elements 7 in the form of spur gears. A common drive shaft 24 carries pinions 25 engaging the spur gears 7 to rotate same in unison about the axis 0, elements 7 being journaled for this purpose in sleeves 2 through the intermediary of roller bearings 8. Thus, platen 5 executes a cycloidal motion parallel to itself as its end gears 4 roll on the inner peripheries of the toothed track members 3; the pitch diameter of gears 4 is shown to equal the outer diameter of the platen.

A printing roller 9 is mounted alongside the platen 5, being journaled in a pair of supporting levers 10 which are swingable about a fixed fulcrum 26. These levers are biased by respective tension springs 11 in a counterclockwise direction (as viewed in FIG. 2), i.e. toward the platen 5, and normally bear upon stops 12 here shown as disks eccentrically carried on a rod 27 on which they are angularly adjustable to vary the position of the roller. The latter is shown to comprise a multiplicity of digit wheel 28 which are individually settable by means of gear teeth 29 under the control of associated sector gears 30, in a manner well known per se in the adding-machine art. Thus, in the embodiment illustrated, each of these wheels is shown to carry ten numerical type faces for the decadic printing of information from associated dataprocessing equipment.

Slidably mounted on frame 1, with the aid of pins 31, are a pair of bars 13 carrying a curved apron 32 which serves as a guide for a sheet of printing paper 18. Apron 32 has a cutout at 33 through which the platen 5 can project into contact with the paper 18. Swingably mounted on each bar 13 is a pawl 14 engaging the teeth of a ratchet 15. A slotted extremity 34 of the bar 13 straddles the corresponding gudgeon 6 so that the two bars oscillate in the direction of arrow 35, FIG. 2, in response to the cycloidal displacement of platen 5. During the withdrawal stroke of this motion, i.e. movement to the left as viewed in FIG. 2, the pawls 14 step the associated ratchets 15 which are rigid with a feed roller 16 co-operating with another roller 17 to advance the sheet 18 through the gap between the platen 5 and the printing roller 9; this feeding operation takes place as the platen approaches its position of maximum separation from the printing roller.

Gudgeons 6 are also in similar engagement with a pair of bars 19 that form part of a frame 36 which supports reels 20, 20' of an ink ribbon 21. Reel 20 is rigid with a ratchet 22 which is stepped by a pawl 23, pivoted on machine frame 1, whenever the frame 36 follows the motion of platen 5 away from roller 9; pawl 23 is under tension of a biasing spring 37. A retaining pawl 38 prevents reverse rotation of ratchet 22; such retaining pawl may, of course, also be provided for the ratchet 15. A spring-loaded arm 39 bears upon the part of ribbon 21 which is wound up on reel 20.

With the sheet guide 32 positively secured to slides 13 and with deflecting rollers 40 for ribbon 21 mounted on slides 19, both the sheet 18 and the ribbon 21 will move away from roller 9 in step with the platen 5, thus allowing the type wheels 28 to be freely reset between printing operations.

Although the displacement of any peripheral point of platen 5 may generally be described as cycloidal, this motion may degenerate to a linear reciprocation in a radial plane through axis in the specific case in which the pitch diameter of planetary gears 4, as well as the platen diameter, equals half the pitch diameter of ring gears 3. It will, however, be generally preferably to choose a different tooth ratio, particularly one in which the numbers of teeth of the two gears are relative primes so that different surface portions of platen confront the printing roller 9 during successive revolutions.

Naturally, our invention is susceptible of numerous modifications without departing from the spirit and scope of the appended claims.

We claim:

1. In a data-recording machine, in combination:

a cylindrical platen;

a carrier member defining a character axis alongside said platen settable about said axis to present selected characters to said platen;

a pair of drive elements at opposite ends of said platen synchronously rotatable about a common drive-element axis, said platen being articulated to said drive elements at locations offset from said drive element axis whereby rotation of said drive elements is translated into a periodic motion of said platen parallel to itself toward and away from said carrier member;

a pair of stationary annular track members centered on said common drive element axis at opposite ends of said platen, the latter being provided with coaxial circular end formations in rolling contact with the inner peripheries of said track members;

guide means for a recording medium interposable between said platen and said carrier member to register said selected characters on said medium in a position of closest approach of said platen to said carrier member; and

mechanism enabling independent movement of said characters about said character axis and said drive elements about said drive-element axis in positions of said latter other than said position of closest approach.

2. The combination defined in claim 1 wherein said carrier member is provided with resilient mounting means yieldably urging said carrier member toward said platen.

3. The combination defined in claim 1 wherein said guide means is coupled with said platen for withdrawing said recording medium from said carrier member upon said platen leaving said position of closest approach.

4. The combination defined in claim 1, further comprising feed means coupled with said driving elements for advancing said recording medium through the gap between said platen and said carrier member in a position of substantial separation thereof.

5. The combination defined in claim 4 wherein said platen is provided with a pair of gudgeons engaging said drive elements at said offset locations, said feed means including a linkage coupled with at least one of said gudgeons.

6. The combination defined in claim 1 wherein said carrier member is a printing roller, further comprising supporting means for an ink ribbon interposable between said printer roller and said recording medium, said supporting means being coupled with said platen for withdrawing said ink ribbon from said printing roller upon said platen leaving said position of closest approach.

7. The combination defined in claim 6 further comprising transport means coupled with said driving elements for advancing said ink ribbon in a position of substantial separation of said platen from said printing roller.

8. The combination defined in claim 7 wherein said platen is provided with a pair of gudgeons engaging said drive elements at said offset locations, said transport means including a linkage coupled with at least one of said gudgeons.

9. The combination defined in claim 1 wherein at least one of said track members is a ring gear and the corresponding end formation is a planetary gear in mesh with said ring gear.

10. The combination defined in claim 9 wherein the numbers of teeth of said ring and planetary gears are relative primes.

References Cited UNITED STATES PATENTS 2,107,142 2/1938 Crosman 10 1-102 2,799,221 7/1957 Olivetti 101-93 2,858,536 10/1958 Johnston 101-93 2,885,956 5/1959 Ash et al. 101-93 2,910,936 11/1959 Cristoff et a1. 101-93 2,915,968 12/1959 Witt et al. 101-93 3,023,698 3/1962 Miller 10 1-336 X WILLIAM B. PENN, Primary Examiner US. Cl. X.R. 

